Common Tree and Shrub Diseases in North Carolina

Healthy green shrubs

We know the feeling when your plant isn’t looking its best. Sometimes all it takes is a little more water or a little more sun. That will usually do the trick. However, if that doesn’t help your plant, it could be a bigger issue – like a disease.

To help you diagnose your plant’s problem, we’ve put together below a list of some common plant diseases. Just click on one of the links below to learn about these diseases that can affect your plants.

  • Canker
  • Leaf Gall
  • Leaf Spot
  • Powdery Mildew
  • Root Rot
  • Shothole
  • Sooty Mold


Canker develops where there has been damage to the bark of a tree or shrub. This could be from insects, sun scald, pruning, cold injury, or mechanical injury. The infection spreads and can girdle a branch causing the branch to fall off or it can girdle a trunk and cause death. Many times the infection is isolated by a corky bark growth from the plant and the plant survives. Damaged areas are best removed as this part of the plant is weakened and could lead to more damage in the future.


Root Rot

This is a soil-born disease that can stay in the soil in decaying organic matter, be carried by wind or water, and infect any host that has been stressed from any number of environmental or mechanical injuries. The best defense against these diseases is planting species that are not susceptible or minimizing any un-needed or avoidable stress during the life of the plant.


Leaf Gall

Galls are growths on plants. They can be simple or complex growths on leaves or stems. Some are brightly colored. In most cases, they are unsightly but harmless to the plants. Some galls form when insects (certain wasps, midges, and aphids) or mites feed on or lay eggs in leaves, twigs, and stems. When feeding or laying eggs the insects can inject a toxin that stimulates rapid and abnormal growth.



This is not really a fungus but actually a bacterial infection. It is not usually a serious problem but if it becomes a problem the severity can be reduced by limiting overhead irrigation. This can also be treated with a bacterial spray.


Leaf Spot

There are thousands of leaf-spotting fungi and bacteria, most of which cause only cosmetic damage. Many of these organisms infect only one plant species. Fungal spores are spread by wind and water splashing the spores onto a leaf. Spots form wherever the fungus infects the leaf. This makes the spots very difficult to totally control but the plants can be protected with a fungicide to keep the leaf spot from defoliating the plant.


Sooty Mold

Sooty molds grow from excretions (honeydew) that come from aphids, mealy bugs, and soft scales as they feed on the plants. This is a sign that there are or were insects feeding on the plants or a plant above that the honeydew has dropped from.

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